Are Hybrid Sunscreens Safe?
Wearing any sunscreen - mineral or chemical - is better than going without it. But how about mixing mineral sunscreen and chemical sunscreen? Or using a hybrid product that uses zinc oxide with small-molecule UV filters? Will the mixture work better in maximizing protection or have the opposite effect? A study found that sunscreens that are effective on their own may lose their effectiveness when combined. Certain combinations may also cause toxic byproducts.
A mix of chemical and mineral filters can degrade organic UV filters
It is well known that zinc oxide sunscreens are generally safer and better tolerated than organic sunscreens. But the efficacy and even safety of a physical sunscreen may alter if it is put on top of or under another organic sunscreen. In a study, researchers found that most of the UV rays are not blocked as effectively as either product working alone. The mix would degrade the organic UV filters, decreasing their effectiveness and creating potentially toxic products.
The study was performed on zebrafish, which share remarkable genetic similarities with humans, and are therefore a near-ideal model for studying human diseases. It found that, upon exposing zebrafish to sunlight for two hours, zinc oxide destroys the UVA protection that other ingredients provide. This would mean that people who believe they're maximizing protection with chemical and mineral filters, and therefore staying out in the sun for longer, may actually be unprotected against UV rays.
The study's lead researcher voiced concern over how the individual ingredients in formulations react with each other during use, and a lack of testing in this regard in the industry. The findings of the study are important when we consider the wide-ranging effects of UVA and UVB rays on the skin, from sunburn and premature skin aging to tanning, pigmentation, and skin cancer.
Even a small amount of zinc oxide, when mixed with organic sunscreen, can reduce UVA protection substantially
The research team tested ingredients in five sunscreens with SPF of 15. They tested the effectiveness and safety of the chemical formulas when combined with zinc oxide and left out in the sun for two hours. The UVA protection factor in the sunscreen mixed with zinc oxide particles decreased by over 80% and up to 92% while the sunscreen without zinc oxide showed a loss in UVA protection of about 16% after the exposure period.
The findings also indicate that small-molecule-based sunscreen, which typically contain organic compounds that absorb UV rays, don't degrade much in the sun. However, the study tested only the main UV-blocking ingredients and not the sunscreens. Researchers said that the other chemicals and preservatives used in sunscreens may alter the results and require further investigation.
The toxicity resulting from the mix produced morphological defects in the fish
Researchers exposed zebrafish embryos to chemical and zinc oxide mixtures in various combinations for a period of five days in the sun. The mixtures containing zinc oxide were observed higher levels of toxic byproducts in the embryos. While the zebrafish did not die due to the resulting toxicity, they demonstrated morphological defects.
Researchers noted that zinc oxide particles, in combination with organic ingredients, may increase the toxicity of sunscreens in ways that aren't currently recognized. But is this alone enough reason to avoid mixing zinc oxide with other sunscreens?
Reapplying sunscreen an effective and potentially safer option
A single study may not be enough to implicate mineral-chemical sunscreen mixing. There is a need for information on the mechanism by which the breakdown happens. Also, as the study involved only UV-blocking ingredients and did not replicate commercial sunscreens, not having information on additives, fragrances, and the exact measurements of ingredients, the impact of mixing products is not completely clear.
What is worth noting from the study is that zinc oxide, which has few FDA-approved alternatives in the US, can break down and produce a number of toxic chemicals. The case is a bit different in Europe, which has other inorganic ingredients approved for use as a UV filter and those result in less degradation comparatively.
The main takeaway, however, is that mixing chemical and mineral sunscreen filters is not a substitute to reapplying sunscreen for effective and lasting UV protection. As a rule of thumb, sunscreen must be reapplied after every two hours, and reapplied after sweating or swimming even if it hasn't been two hours yet.
The bottom line
Sunscreen is essential. Daily use and reapplication throughout the day continues being the most effective way to avoid tans or sunburns on scorching days. If your work or lifestyle involves outdoor assignments or activities, sunscreen will help prevent photoaging, doing its bit to keep wrinkles and fine lines away.
Use either a chemical or a physical sunscreen. Avoid hybrid sunscreen that uses both chemical and physical filters. CodeSkin sunscreens use only chemical filters that act gently on the skin and provide strong UV protection. We avoid ingredients on the restricted lists of international organizations. Check out our fabulous products here:
Leave a comment
This site is protected by hCaptcha and the hCaptcha Privacy Policy and Terms of Service apply.